Lateral insertion spinal implant

ABSTRACT

The present disclosure relates to a spinal implant. The spinal implant may be used for lateral insertion into an intervertebral disc space. For example, the spinal implant may include a spacer body to which a plate is fixed. The intervertebral spacer body may include a pair of opposite sides having a pyramid-shaped teeth to fuse to bone. The plate defines at least one upper and lower borehole that each receives a screw. Each screw attaches the plate to a vertebral body between which the intervertebral spacer body is inserted. The boreholes may include locking threads that are adapted to lock the screws into place by engaging complementary locking threads of head of the screw.

RELATED APPLICATION

This application claims the benefit of provisional application Ser. No.61/666,335 filed on Jun. 29, 2012, entitled “LATERAL INSERTION SPINALIMPLANT,” the entire disclosure of which is hereby incorporated byreference.

BACKGROUND

Spondylolisthesis is a term used to describe when one vertebrae slipsforward on the vertebrae below it. This usually occurs because there isa spondylolysis in the superior vertebrae. There are two main parts ofthe spine that keep the vertebrae aligned, which include the disc andthe facet joints. When spondylolysis occurs, the facet joint can nolonger hold the vertebrae back. The intervertebral disc may slowlystretch under the increased stress and allow the upper vertebra to slideforward. In the vast majority of cases, stretching of the intervertebraldisc only allows for a small amount of forward slip.

Surgical treatment for spondylolisthesis needs to address both themechanical symptoms and the compressive symptoms, if they are present.The goals of surgery are to remove pressure on spinal nerves (i.e.,decompression) and to provide stability to the thoracic/lumbar spine. Inmost cases of spondylolisthesis, decompression should be accompanied byuniting one spinal vertebrae to the next (i.e., spinal fusion) withspinal instrumentation (i.e., implants that are often used to help aidthe healing process).

In other cases, the spinal disc and/or vertebral bodies may be displacedor damaged due to trauma, disease, degenerative effects, or wear over anextended period of time. This displacement or damage often causeschronic back pain. In order to alleviate the chronic back pain, a spinaldisc is removed, along with all or part of at least one of theneighboring vertebrae. An implant is then inserted to promote fusion ofthe remaining bony anatomy. The success of spinal fusion is limited,however, due to several factors. For example, the spacer or implant orcage used to fill the space left by the removed disc may not be strongenough to support the spine. Furthermore, the spacer must be able toremain in the position in which it is placed by the surgeon. The spacemust also be comprised of such a material to promote bony growth aroundthe spacer and within the spinal region.

SUMMARY

The present disclosure relates to spinal implants. For example, thespinal implants may be used for insertion into the intervertebral discspace. The spinal implants may also be used for alleviating chronic backpain and promoting bony growth around the spinal implants. The spinalimplants may also be positioned between two vertebral bodies and securedwith at least two locking screws.

An example spinal implant includes an intervertebral spacer body, aplate, and at least two screws. The intervertebral spacer body includesa pair of opposite sides. The plate comprises a front surface and a rearsurface. The plate is configured to attach to vertebral bodies by atleast two screws. For example, the plate includes at least one upperborehole and at least one lower borehole for attachment of the plate tothe vertebral bodies. The plate may comprise at least two lowerboreholes and the at least two upper boreholes, which are off-centeredabout the centerline of the plate.

The plate is configured to mate with the intervertebral spacer body. Aportion of the rear surface of the plate is adapted to contact a wall ofa vertebral body. Each borehole comprises a threaded region adapted toengage a complementary threaded region of a head of a screw insertedtherethrough at a fixed angle relative to the plate. Further, the screwsinserted into the at least two upper boreholes and the at least twolower boreholes have divergent angles. The screws diverge asymmetricallyabout a transverse midline of the plate.

The pair of opposite sides of the intervertebral spacer body may alsocontact two vertebral bodies. The anterior portion of the intervertebralspacer body optionally curves medially. The screws may include at leasttwo anterior screws and at least two posterior screws.

The spinal implant may also include screws that are locking screws. Theplate optionally has conical locking threads in the boreholes. Thelocking screws may be screwed into the plate and locked into the conicallocking threads in the boreholes. The screws, locking or non-locking,may also be inserted into the first and second vertebral bodies atdivergent angles, or where the screws diverge either symmetrically orasymmetrically about the transverse midline.

The intervertebral spacer body may also include a plurality ofprotrusions. These protrusions optionally secure the intervertebralspacer body between the first and second vertebral bodies. The plate ofthe spinal implant may also include at least three boreholes, and inother embodiments, it may contain at least two boreholes.

These and other features and advantages of the implementations of thepresent disclosure will become more readily apparent to those skilled inthe art upon consideration of the following detailed description andaccompanying drawings, which describe both the preferred and alternativeimplementations of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference numbers and designations in the variousdrawings indicate like elements.

FIG. 1 is a perspective view of an example spinal implant;

FIGS. 2A-2F illustrate a first embodiment of a spacer body that may beused to construct the spinal implant of FIG. 1;

FIGS. 3A-3F illustrate a second embodiment of a spacer body that may beused to construct the spinal implant of FIG. 1;

FIGS. 4A-4F illustrate a third embodiment of a spacer body that may beused to construct the spinal implant of FIG. 1;

FIGS. 5A-5F illustrate a fourth embodiment of a spacer body that may beused to construct the spinal implant of FIG. 1;

FIGS. 6A-6H illustrate a plate in accordance with a first embodiment ofthe present disclosure;

FIGS. 7A-7H illustrate a plate in accordance with a second embodiment ofthe present disclosure;

FIG. 8 illustrates a plate in accordance with a third embodiment of thepresent disclosure;

FIG. 9 illustrates a plate in accordance with a fourth embodiment of thepresent disclosure;

FIGS. 10A-10C illustrates a first embodiment of a screw of the presentdisclosure;

FIGS. 11A-11B illustrate a second embodiment of a screw of the presentdisclosure;

FIGS. 12A-12B illustrate an example sequence of assembly of the spinalimplant of FIG. 1;

FIG. 13 illustrates the assembled spinal implant of FIG. 1, togetherwith screws inserted therein;

FIGS. 14A-14C, 15A-15B, 16A-16D, 17A-17C illustrate the example spinalimplant, as generally positioned in the intervertebral disc spacebetween two vertebral bodies;

FIGS. 18A-18B illustrate a comparison of access windows during a spinalimplant procedure using various plates of the present disclosure;

FIGS. 19A-19C illustrate another spinal implant of the presentdisclosure;

FIG. 20 illustrates another spinal implant of the present disclosure;

FIGS. 21A-21D illustrate another spinal implant of the presentdisclosure; and

FIGS. 22A-22C illustrate views of another embodiment of a spinal implantof the present disclosure.

DETAILED DESCRIPTION

Implementations of the present disclosure now will be described morefully hereinafter. Indeed, these implementations can be embodied in manydifferent forms and should not be construed as limited to theimplementations set forth herein; rather, these implementations areprovided so that this disclosure will satisfy applicable legalrequirements. As used in the specification, and in the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessthe context clearly dictates otherwise. The term “comprising” andvariations thereof as used herein is used synonymously with the term“including” and variations thereof and are open, non-limiting terms.

In performing a wide range of back surgeries, surgeons are oftenrequired to make use of pedicle screws and rods. These pedicle screwsand rods are components of rigid stabilization systems, which tend to beintrusive to surrounding tissue and vasculature systems. The presentdisclosure is less intrusive because this spinal implant not only isconformable to the spinal anatomy, but also is strong enough to allowsurgeons to avoid using pedicle screws and rods. The present disclosurealso allows for less invasive surgery and quicker surgery time.

FIGS. 1-18 illustrate the different views of an embodiment of thepresent disclosure. An example spinal implant 100A is shown in FIG. 1.FIG. 1 serves as an introduction to the components and features of thespinal implant 100A. Details of the various components of the spinalimplant 100A are illustrated in FIGS. 2-11. The spinal implant 100Aincludes an intervertebral spacer body 102 and a plate 106. Theintervertebral spacer body 102 includes a pair of opposite sides 104.Each opposite side 104 optionally has pyramid-shaped teeth 118 that areprovided to frictionally engage top and bottom surfaces of a vertebralbody. The intervertebral spacer body 102 may include a central window117 and side windows 116. Tantalum markers may be provided proximate tothe central and side windows 116. A surgeon or any other medicalprofessional may take radiographs of the area in which a spinal implant100A is placed to view the tantalum markers to insure proper placementof the implant 100A in a patient's body. The intervertebral spacer body102 may include a self-distracting bulletnose 120. The intervertebralspacer body 102 is optionally made of polyether ether ketone (PEEK), anyother biocompatible materials appropriate for medical implants.

The plate 106 is comprised of a front surface and a rear surface. Theplate 106 may include at least two upper boreholes 110 and at least twolower boreholes 110, respectively positioned about a centerline andthrough the front surface and the rear surface of the plate 106. The atleast two upper boreholes 110 and the at least two lower boreholes 110may have one or more alignments within the plate 106 and with respect tothe centerline of the plate 106. A further discussion of the boreholes110 is provided below with reference to FIGS. 6-9. The plate 106 furtherincludes coupling flanges 114 that are adapted to be coupled to thespacer body 102. The plate 106 may also define a region to mate with theintervertebral spacer body 102. For example, a portion of the rearsurface of the plate 106 is adapted to contact a wall of the vertebralbody. A central hole 124 is provided as an insertion region into which ascrew (not shown) may be inserted to secure the plate 102 to the spacerbody 102 and/or attachment of an appropriate insertion device. The plate106 may comprise TAN, any other titanium alloy appropriate for surgicalor medical devices, or any other appropriate material.

One or more screws 108 attach the plate 106 to the vertebral bodies andto secure the intervertebral spacer body 102 therein between. The screws108 optionally comprise a titanium-6 aluminum-7 niobium alloy (TAN), anyother titanium alloy appropriate for surgical or medical devices, or anyother appropriate material.

As will be described with reference to FIGS. 2-7, the first embodimentof the spinal implant 100A include many different combinations of spacerbodies 102A-102D and plates 106A-106D. In particular, the various spacerbodies 102A-102D are illustrated in FIGS. 2-5, which may beinterchangeably attached with the plates 106A-106D illustrated in FIGS.6-9 to create a spinal implant 100A having a configuration adapted foruse in a specific regions of the spinal column.

FIGS. 2A-2F illustrate a first embodiment of a spacer body 102A that maybe used to construct the spinal implant 100A of the present disclosure.As illustrated in FIGS. 2A and 2D, the spacer body 102A includes agenerally rounded distal end 128A and a proximal end 129A that defines abase 138A that is adapted to engage the coupling flanges 114 of theplate 106. The spacer body 102A has either straight or non-straightsides 130A and 132A and a central window 117A. The central window 117Ais generally an oval shape, but can be any shape or shapes, such as oneor more circular regions, rectangular regions, polygon-shaped regions,etc. The central window 117A may promote the growth of a bony bridgebetween adjacent vertebral bodies within which the spacer body 102A isinserted. In accordance with the first embodiment, the spacer body 102Amay have a width W of approximately 18 mm and a length L ofapproximately 35 to 55 mm. Thus, the spacer body 102A may have a lengthto width ratio of approximately 1.8-3.2 when used for, e.g., lateralprocedures.

As shown in the cross sectional view of FIG. 2B and the magnified viewof FIG. 2C, the top surface 134A and the bottom surface 136A have aradius of curvature denoted R_(1A), and R_(2A), respectively between thesides 130A and 132A. Thus, the top surface 134A and the bottom surface136A are slightly curved in a lateral direction of the spacer body 102A.The radius of curvature R_(1A), and R_(2A) may be the same or differentto achieve a secure fit with an adjacent vertebral body. FIGS. 2B and 2Cillustrate pins 126A, which may be viewed using an appropriate imagingdevice to confirm the location of the spinal implant 100A when insertedinto a patient's body. The pins 126A may have a width of approximately0.8 mm and may be made from, e.g., stainless steel or other materialthat is visible when exposed to, e.g., x-rays.

As shown in FIGS. 2D and 2E, the top surface 134A and the bottom surface136A of spacer body 102A also have a radius of curvature R_(3A) andR_(4A), respectively, between the distal and 128A and the proximal end129A. As such, the top surface 134A and the bottom surface 136A areslightly curved in the longitudinal direction of the spacer body 102A.The radius of curvature R_(3A) and R_(4A) may be the same or differentto achieve a secure fit with an adjacent vertebral body. The curvatureof the top surface 134A and bottom surface 136A in the lateral and/orlongitudinal directions provides a shape that may be received withinnatural contours of the vertebral bodies.

FIGS. 2D and 2E also illustrate the side windows 116A and thepyramid-shaped teeth 118A in greater detail. The side widows 116A mayhave any suitable geometry, including but not limited to, oval, oblong,rectangular, triangular, circular, polygonal and/or any combinationthereof. The teeth 118A may have other shapes suitable for engaging thevertebral bodies. Recesses 140A are defined in the sides 130A and 132Areceive inward pointing projections 150A/150B and 152A/152B (see, FIGS.6-7) of the coupling flanges 114 in order to snap the plate 106 securelyinto place on the spacer body 102A. In some implementations, the recess140A extend along only a portion of the side walls 130A and 132A. Inaccordance with the present disclosure, the spacer body 102A may have aheight H of approximately 6 mm to 17 mm.

FIG. 2F illustrates view of the proximal end 129A of the spacer body102A. The base 138A is defined having a width that is narrower than theoverall width of the spacer 102A (see, FIG. 2A), such that when thecoupling flanges 114 are joined thereto, the overall width of the base138A and the coupling flanges 114 is approximately equal to the width ofthe spacer body 102A. For example, the width of the base 138A may besized such that may be securely grasped between the coupling flanges 114of the plate 106. The base 138A may further define a hole 139A which mayreceive a screw (not shown) used to secure the plate 106 to the spacerbody 102A, either solely for insertion or for long term connection.

Thus, as shown in FIGS. 2A-2F and described above, a medical specialistcan select an appropriately sized spacer body 102A in accordance withthe void between adjacent vertebral bodies into which the spacer bodywill be inserted.

FIGS. 3A-3F illustrate a second embodiment of a spacer body 102B thatmay be used to construct the spinal implant 100A of the presentdisclosure. Aspects of the spacer body 102B that are substantiallysimilar to the first embodiment of the spacer body 102A will not berepeated.

As shown in the cross sectional view of FIG. 3B and the magnified viewof FIG. 3C, the top surface 134B and the bottom surface 136B each aresubstantially flat. As shown, the side 132B has a height of h₁ and theside 130B has a height of h₂. Thus, the top surface 134A and the bottomsurface 136A form an angle α that is defined by the heights h₁ and h₂.In accordance with the present disclosure the heights h₁ and h₂ mayrange from approximately 5 mm to 17 mm.

As shown in FIG. 3E, a recess 140B defined in the side 130B extendsalong the entirety of the side wall 130B, where a recess 140B formed inthe side 132B extends along a portion of the side 132B (see, FIGS. 3Aand 3D).

FIG. 3F illustrates view of the proximal end 129B of the spacer body102B. The base 138B is defined having a width that is narrower than theoverall width of the spacer 102B (see, FIG. 3A), such that when thecoupling flanges 114 are joined thereto, the overall width of the base138B and the coupling flanges 114 is approximately equal to the width ofthe spacer body 102B. The base 138B may further define a hole 139B whichmay receive a screw (not shown) used to secure the plate 106 to thespacer body 102B. As illustrated, the base 138B is formed having at thesame angle α that is defined by the heights h₁ and h₂ of the sides 132Band 130B, respectively.

Thus, as shown in FIGS. 3A-3F and described above, a medical specialistcan select an appropriately sized spacer body 102B in accordance withthe void between adjacent vertebral bodies into which the spacer bodywill be inserted.

FIGS. 4A-4F illustrate a third embodiment of a spacer body 102C that maybe used to construct the spinal implant 100A of the present disclosure.Those aspects of the third embodiment of the spacer body 102C that aresubstantially similar to the first embodiment of the spacer body 102Awill not be repeated below. As illustrated in FIGS. 4A and 4D, thespacer body 102C includes a generally rounded distal end 128C and aproximal end 129C that defines a base 138C that is adapted to engage thecoupling flanges 114 of the plate 106. The spacer body 102C has curvedsides 130C and 132C and a central window 117C. In accordance with thethird embodiment, the spacer body 102C may have a width W ofapproximately 22 mm (as measured between the widest points) and a lengthL of approximately 35 to 55 mm. Thus, the spacer body 102C may have alength to width ratio of approximately 1.59-2.5 when used for, e.g.,lateral procedures.

Thus, as shown in FIGS. 4A-4F and described above, a medical specialistcan select an appropriately sized spacer body 102C in accordance withthe void between adjacent vertebral bodies into which the spacer bodywill be inserted.

FIGS. 5A-5F illustrate a fourth embodiment of a spacer body 102D thatmay be used to construct the spinal implant 100A of the presentdisclosure. Aspects of the spacer body 102D that are substantiallysimilar to the second embodiment of the spacer body 102B will not berepeated.

As illustrated in FIGS. 5A and 5D, the spacer body 102C includes curvedsides 130C and 132C and a central window 117C. In accordance with thefourth embodiment, the spacer body 102D may have a width W ofapproximately 22 mm (as measured between the widest points) and a lengthL of approximately 35 to 55 mm. Thus, the spacer body 102D may have alength to width ratio of approximately 1.59-2.5 when used for, e.g.,lateral procedures.

Thus, as shown in FIGS. 5A-5F and described above, a medical specialistcan select an appropriately sized spacer body 102D in accordance withthe void between adjacent vertebral bodies into which the spacer bodywill be inserted.

FIGS. 6A-6H illustrate a plate 106A in accordance with a firstembodiment of the present disclosure. The first embodiment illustrates aso-called “asymmetric plate” in accordance with the present disclosure.FIGS. 6A and 6B, respectively, illustrate front and rear perspectiveviews of the plate 106A. The plate 106A includes sides 158A and 160A, arear surface 162A and a front surface 164A. Circular recesses 157A maybe formed in the sides 158A and 160A of the plate 106A. A central hole124A is provided into which a screw (not shown) may be inserted tosecure the plate 106A to the various spacer bodies described above. Thecentral hole 124A may be formed within a keyed recess 163A.

In FIG. 6B, there is shown the coupling flanges 114A and theirassociated inward pointing projections 150A and 152A. As noted above,the projections 150A and 152A are received within the recesses 140 ofthe base 138 of the spacer bodies 102, as described above. The couplingflanges 114A extend from a substantially flat wall 166A that abuts thebase 138 of the spacer body 102 when the plate 106A is attached thereto.As shown in FIGS. 6A and 6B, the boreholes 110 _(A1) to 110 _(A4) mayinclude locking threads 112A that are adapted to receive complementarythreads of the screws 108.

Referring now to FIG. 6C, there is shown a side view of the plate 106Ashowing the side 160A. The lower boreholes 110 _(A2) and 110 _(A4) maybe have a central axis 153A that is formed at an approximately 5° anglewith respect to a first horizontal axis 154A passing through the centerof the boreholes 110 _(A2) and 110 _(A4) that parallels a lateral centerplane 161A of the plate 106A. As shown in the side view of FIG. 6Dillustrating the side 158A, the upper boreholes 110 _(A1) and 110 _(A3)may have a central axis 155A that is formed at an approximately 20°angle with respect to a second horizontal axis 156A passing through thecenter of the boreholes 110 _(A1) and 110 _(A3) that parallels thelateral center plane 161A.

As will be shown in FIGS. 15A-16B the above offsets of the central axiscauses the screws 108 inserted therein to diverge at asymmetric anglesabout the lateral center plane 161A of the plate 106A. It is noted thatcentral axis 153A and 155A of the lower and upper boreholes may beoffset at any angle between 5° and 20° with respect to the horizontalaxis 154A and 156A. It is also noted that central axis of the upperboreholes and lower boreholes may be at the same angle with respect tothe horizontal axis 154A and 156A, thus causing the screws insertedtherein to diverge at symmetrically angles about the lateral centerplane 161A of the plate 106A.

FIG. 6F illustrates a cross-sectional view of the lower boreholes 110_(A2) and 110 _(A4) shown in FIG. 6C. FIG. 6E illustrates across-sectional view of the upper boreholes 110 _(A1) and 110 _(A3)shown in FIG. 6D. As illustrated in FIGS. 6E and 6F, locking threads112A are defined within the boreholes 110 _(A1)-110 _(A4) to threadedlyengage with complementary locking threads of the head of the screw 108.In accordance with the first embodiment, the upper and lower boreholes110 _(A3) and 110 _(A4) may have a central axis 155A and 153A that arelaterally offset at approximately a 3° angle with respect to the secondhorizontal axis 156A and first horizontal axis 154A, respectively,passing through the center of the boreholes 110 _(A3) and 110 _(A4). Theupper and lower boreholes 110 _(A1) and 110 _(A2) formed proximate tothe side 158A may have a central axis 155A and 153A that are laterallyoffset at approximately a 1° angle with respect to the second horizontalaxis 156A and first horizontal axis 154A, respectively, passing throughthe center of the boreholes 110 _(A1) and 110 _(A2). The firsthorizontal axis 154A and the second horizontal axis 156A parallel alongitudinal central plane 165A (see, also FIG. 6H) of the plate 106A.

Each of the boreholes 110 _(A1)-110 _(A4) may be tapered such that it iswider proximate to the front surface 164A than proximate to the rearsurface 162A forming a conical surface therein. As such, a screwinserted having a complementary taper will stop at a predeterminedposition within the plate 106A. As shown, the centers of boreholes 110_(A1) and 110 _(A2) may be positioned 5.3 mm from a center of the plate106A, whereas the boreholes 110 _(A3) and 110 _(A4) may be positioned5.5 mm from the center of the plate 106A, as defined by the longitudinalcentral plane 165A.

Referring now to FIG. 6G, there is illustrated a top view of the plate106A. The rear surface 162A forms a curved surface moving longitudinallyfrom a top 170A of the plate 106A to the flat wall 166A (see, also FIG.6B). Although not shown in FIG. 6G, the rear surface 162A forms asimilar curved surface moving longitudinally from a bottom 172A of theplate 106A to the flat wall 166A. As illustrated, the top surface 170Ais generally medially curved from the side 158A to the side 160A,forming a region 174A that substantially matches a curvature an outerwall of a superior vertebral body. A similar curved region is formedfrom the side 158A to the side 160A proximate to the bottom 172A thatsubstantially matches a curvature an outer wall of an inferior vertebralbody. In particular, the curved region 174A (and lower curved region(not shown)) may have a portion thereof having a radius of curvatureR_(6A) formed proximate to the edge of the front surface 164A and theside 160A. In addition, the edge formed by the front surface 164A andthe side 158A may be formed having a radius of curvature R_(5A).

As shown in FIG. 6G, in some implementations, the coupling flanges 114Amay be of unequal length. The coupling flanges 114A may each have theinward pointing projections 150A and 152B, respectively, as describedabove, for engaging the recesses 140 of the spacer body 102. Forexample, a flange extending alongside 158A may have a length of 15 mm,as measured from the front surface 164A. A flange extending alongside160A may have a length of 13 mm, as measured from the front surface164A. The flanges may be formed having equal lengths, or any combinationof lengths between 12 mm and 16 mm. The inner walls of the flanges maybe separated by distance H_(F) of 14 mm. The distance H_(F) may be anyvalue that is substantially equal to a width of the base 138 of thespacer bodies described above. The width W of the plate 106A isapproximately 19 mm.

FIG. 6H illustrates a front view of the plate 106A. As illustrated, theupper boreholes 110 _(A1) and 110 _(A3) may be located a distance D_(U)from the lateral center plane 161A and about the longitudinal centerplane 165A. Lower boreholes 110 _(A2) and 110 _(A4) may be located adistance D_(L) from a lateral center plane 161A and about thelongitudinal center plane 165A. The distance D_(U) may range fromapproximate 2.75 mm to 6.75 mm. The distance D_(L) may range fromapproximately 6 mm to 10 mm. Thus, the ratio of D_(L):D_(U) isapproximately 1.4 to 2.2. The plate 106A may have a height H that rangesfrom approximately 18 mm to 26 mm. The distance Q between the outeredges of the boreholes in a vertical direction may range fromapproximately 15 mm to 23 mm, thus providing approximately 1.5 mm ofmaterial between the outer edge of the borehole and the edge of theplate 106A. The distance U between the inner edges of the boreholes mayrange from approximately 2.5 mm to 10.5 mm. Also as shown in FIG. 6H,the front surface 164A defines a substantially rectangular region havingdimples 176A and 178A formed along the outer edges of the plate 106Abetween the boreholes. The plate 106A may have a width of approximately18 mm, as measured between the dimples formed in the sides 158A and160A. Thus, the dimples 176A and 178A remove approximately 1 mm ofmaterial, reducing the weight of the plate 106A.

Thus, as shown in FIGS. 6A-6H and described above, a medical specialistcan select an appropriately sized plate 106A in accordance with alocation of the spine into which the spinal implant 100A is to beimplanted and an access window to perform the spinal implant procedure.

FIGS. 7A-7H illustrate a plate 106B in accordance with a secondembodiment of the present disclosure. The second embodiment illustratesa so-called “symmetric plate” in accordance with the present disclosure.Those aspects of the second embodiment of the plate 106B that are thesame as the first embodiment of the plate 106A will not be repeatedbelow.

FIGS. 7A and 7B, respectively, illustrate front and rear perspectiveviews of the plate 106B. The plate 106B includes sides 158B and 160B, arear surface 162B and a front surface 164B. A central hole 124B isprovided into which a screw (not shown) may be inserted to secure theplate 106B to the various spacer bodies described above.

Referring now to FIG. 7C, there is shown a side view of the plate 106Bshowing the side 160B. The lower boreholes 110 _(B2) and 110 _(B4) mayhave a central axis 153B that is formed at an approximately 20° anglewith respect to a first horizontal axis 154B passing through the centerof the boreholes 110 _(B2) and 110 _(B4) that parallels a lateral centerplane 161B of the plate 106B. As shown in the side view of FIG. 7Dillustrating the side 158B, the upper boreholes 110 _(B1) and 110 _(B3)may have a central axis 155B that is also formed at an approximately 20°angle with respect to a second horizontal axis 156B passing through thecenter of the boreholes 110 _(B1) and 110 _(B3) that parallels thelateral center plane 161B.

As will be shown in FIGS. 14A-14B the above offsets of the central axiscauses the screws 108 inserted therein to diverge at symmetric anglesabout the lateral center plane 161B of the plate 106B. It is noted thatcentral axis 153B and 155B of the lower and upper boreholes may beoffset at any angle between 5° and 20° with respect to the horizontalaxis 154B and 156B.

FIG. 7H illustrates a front view of the plate 106B. As illustrated, theupper boreholes 110 _(B1) and 110 _(B3) may be located a distance D_(U)from the lateral center plane 161B and about the longitudinal centralaxis 165B. Lower boreholes 110 _(B2) and 110 _(B4) may be located adistance D_(L) from a lateral center plane 161B and about thelongitudinal central axis 165B. The distance D_(U) may range fromapproximate 2.75 mm to 6.75 mm. Similarly, the distance D_(L) may rangefrom approximately 2.75 mm to 6.75 mm. Because of the symmetric shape ofthe plate 106B, the ratio of D_(L):D_(U) is maintained at 1, thus D_(L)and D_(U) are equal for all sizes of D_(L) and D_(U) implemented in theplate 106B. The plate 106B may have a height H that ranges fromapproximately 15 mm to 23 mm. The distance Q between the outer edges ofthe boreholes in a vertical direction may range from approximately 12 mmto 20 mm, thus providing approximately 1.5 mm of material between theouter edge of the borehole and the edge of the plate 106B. The distanceU between the inner edges of the boreholes may range from approximately0.5 mm to 8.5 mm. Also as shown in FIG. 7H, the front surface 164Bdefines a substantially rectangular region having dimples 176B and 178Bformed along the outer edges of the plate 106B between the boreholes.The plate 106B may have a width of approximately 18 mm, as measuredbetween the dimples formed in the sides 158B and 160B. Thus, the dimples176B and 178B remove approximately 1 mm of material, reducing the weightof the plate 106B.

Thus, as shown in FIGS. 7A-7H and described above, a medical specialistcan select an appropriately sized plate 106B in accordance with alocation of the spine into which the spinal implant 100A is to beimplanted and an access window to perform the spinal implant procedure.

FIG. 8 illustrates a plate 106C in accordance with a third embodiment ofthe present disclosure. The plate 106C features a reduced height D_(L)as compared to the plate 106A. For example, the height reduction may beapproximately 2 mm to 4 mm. As illustrated, the upper boreholes 110_(C1) and 110 _(C1) may be located a distance D_(U) from the lateralcenter plane 161C. Lower boreholes 110 _(C2) and 110 _(C4) may belocated a distance D_(L) from a lateral center plane 161A. The distanceD_(U) may range from approximate 2.75 mm to 6.75 mm. The distance D_(L)may range from approximately 3 mm to 7 mm. Thus, the ratio ofD_(L):D_(U) is approximately 0.92 to 1.0. The plate 106C may have aheight H that ranges from approximately 15 mm to 23 mm. The distance Qbetween the outer edges of the boreholes in a vertical direction mayrange from approximately 12 mm to 20 mm, thus providing approximately1.5 mm of material between the outer edge of the borehole and the edgeof the plate 106 c. The distance U between the inner edges of theboreholes may range from approximately 2.5 mm to 10.5 mm. In otheraspects, the plate 106C has substantially the same dimensions andfeatures as the plate 106A.

The plate 106C enables a surgeon or any other medical professionalworking in the spinal region may avoid interference with the iliac crestwhen working near the sacrum using the assembled spinal implant havingthe plate 106C. The plate 106C also allows for the removal of less bonein the event that osteophyte is present. Still further, the plate 106Callows the screws 108, when inserted into the boreholes 110 _(C1)-110_(C4) to penetrate bone that is closer to the disc space, thus reducingexposure of the screws 108 and lessening the risk of the screws 108protruding into the disc space.

FIG. 9 illustrates a plate 106D in accordance with a fourth embodimentof the present disclosure. The plate 106D is similar to the plate 106C;however the plate 106D is configured to be mounted flush to certainportions of the anatomy in the medial-lateral plane, as well as thecranial-caudal plane. As shown, the plate 106D provides for a portion902 in which material associated with the plate 106C that may causeirritation to a patient is removed.

FIGS. 10A-10C illustrates a first embodiment of a screw 108A of thepresent disclosure. The screw 108A includes a threaded head 180A and athreaded body 186A. Thus, the threaded body 186A has relatively coursepitch to provide for sufficient screw purchase into cortical bone of avertebral body. The screw 108A has a variable angled screw point 188Awhere the point is initially angled at approximately 18° and then angledat approximately 22° proximate to a first thread thereof. The head ofthe screw 108A defines a star-shaped recess 181A, into which acomplementary star-shaped driver may be inserted to drive the screw. Therecess may be formed having other shapes, such as a line, a plus sign, asquare or other polygon shape to receive a complementary drive. Thescrew 108A may have a length that may range from 20 mm to 50 mm.

FIGS. 11A-11B illustrate a second embodiment of a screw 108B. The screw108B shares similar features with the screw 108A in size and shape,however has a hollow center 189B into which bone cement or otheradhesive may be injected. The screw 108B may be used in situations wherethe receiving bone is structurally unsound and may not retain the screw108B. The screw 108B may provide for e.g., luer locking of an injectionmechanism within the recess 181B. Bone cement or other adhesive may beinjected into the screw 108B such that it flows within the centralhollow region 189B of the screw 108B and out of the holes 182B into thethreads and surrounding bone to secure the screw 108B within, e.g., avertebral body.

Referring now to FIGS. 12A-12B, there is shown an example sequence ofassembly of the spinal implant 100A using, e.g., spacer body 102C andplate 106B. As illustrated, the plate 106B and the spacer body 102C arecooperatively configured to mate with one another. In the sequence ofFIGS. 12A-12B the coupling flanges 114 are pressed into the recesses140A defined in the sides 130A and 132A to receive the inward pointingprojections 150B and 152B of the coupling flanges 114 in order to snapthe plate 106B securely into place on the spacer body 102C. Thus, thespinal implant 100A is ready for use by a medical specialist as part ofa spinal repair procedure.

Referring now to FIG. 13, there is illustrated the assembled spinalimplant 100A together with screws 108 inserted therein. As illustratedin FIG. 13, the inserted screw heads are partially contained within aspace 1102 defined by the height of the spacer 102 between the topsurface 134 and the bottom surface 136. Such an arrangement provides fora more compact access window area as the screws are position closertogether in a vertical orientation. In accordance with aspects of thepresent disclosure, the engagement of the threaded head 180 and thelocking threads 112 fixes the angles of the screws 108 with respect tothe plate 106.

As will now be described with reference to FIGS. 14-18, the spinalimplant 100 may be laterally inserted into an intervertebral spacebetween two vertebral bodies. For example, the spinal implant 100 may beused to impart superior stability to a lytic spondylolisthesis orprovide structural stability in skeletally mature individuals followingdiscectomies. Embodiments of the present disclosure may be used for workin, around, or within the lumbar sections L1 to L4 or thoracic sectionsT9 to T12. Alternatively, the implant 100 (of varying length to widthratios) may be implanted anteriorly into an intervertebral space betweentwo vertebral bodies.

Referring now to FIGS. 14A-14C, there is illustrated an example spinalimplant as generally positioned in the intervertebral disc space betweentwo vertebral bodies 202 and 204. The spinal implant 100A may includeany of the spacer bodies 102A-102D and the plate 106B, thus providing asymmetric divergence of the screws 108. The boreholes 110 _(B1)-110_(B4) of the plate 106 are located near the corners of the plate 106B,thus positioning the screws 108 to coincide with the portion of thevertebral bodies 202 and 204 that is strongest. The corner portion ofthe plate 106 aligns with the Cortical Rim, thus providing a sufficientamount of cortical bone for the screws 108 to engage to retain theimplant 100 in a desired position.

As shown in FIG. 14B, the upper screws 108 and lower screws 108 divergeat a symmetric angle from a midline 109 of the implant 100. As notedabove, where the screws 108 diverge symmetrically from the midline 109,the screws may diverge at an angle between 10° and 30° for a lateralapproach and between 20° and 45° for an anterior approach with respectto the centerline 109. As shown in FIG. 14C, the anterior screw mayangle posteriorly at an angle that is approximately 0° and 3° and theposterior screw may angle anteriorly at an angle which may beapproximately 0° and 3°, as illustrated in FIGS. 7E and 7F and discussedin detail with regard to FIGS. 6E and 6F and boreholes 110 _(B1)-110_(B4). The divergent angles of the screws are fixed because of theaforementioned engagement of the screw head 180 and locking threads 112,thus increasing the stability of the spinal implant 100 within the body,while avoiding any concerns of the ends of the screws 108 penetratingthe wall of the vertebral body 202 or 204 from the inside out.

Also shown in FIG. 14C, the top surface 170B of the plate 106 isgenerally medially curved such that it substantially matches a curvaturean outer wall of a superior vertebral body. A similar curved region isformed from the side the bottom of the plate 106 that substantiallymatches a curvature an outer wall of an inferior vertebral body. Thus,the plate 106 achieves a better fit with the outer surface of vertebralbodies. For example, the curvature of the plate 106 reduces oreliminates any gap that may exist between the rear surface 162 of theplate 106 and an outer wall of the vertebral bodies 202 and 204, thusproviding more stability (see, region 111).

Referring now to FIGS. 15A-15B, there is illustrated the spinal implant100A as implanted between two vertebral bodies. The spinal implant 100Amay include any of the spacer bodies 102A-102D and the plate 106A, thusproviding an asymmetric divergence of the screws 108. As illustrated,upper screws 108 and lower screws 108 diverge at an asymmetric anglefrom a midline 109 of the implant 100. As shown, the upper screws 108(a)may diverge at an angle between 0° and 10° with respect to thecenterline 109, whereas the lower screws 108(b) may diverge at an anglebetween 10° and 30° with respect to the centerline 109. Theimplementation of FIGS. 15A-15B is useful when working near the iliaccrest because the ‘flatness’ or small angle of the upper screws 108 doesnot interfere with the iliac crest. Although not shown, the anteriorscrew may angle posteriorly and the posterior screw may angleanteriorly, as discussed above with regard to FIG. 14C.

FIGS. 16A-16D illustrate an example spinal implant as generallypositioned in the intervertebral disc space between two vertebral bodies202 and 204. For example, the spinal implant 100 shown in FIGS. 16A-16Dmay be used when working in lumbar or thoracic section of the spine. Thespinal implant 100 may include any of the spacer bodies 102A-102D, asmodified (see discussion with reference to FIG. 16D below) and the plate106C, thus providing an asymmetric divergence of the screws 108. Asshown in FIG. 16B, the upper screws 108 and lower screws 108 diverge atan asymmetric angle from a midline 109 of the implant 100. As shown, theupper screws 108(a) may diverge at an angle between 0° and 10° withrespect to the centerline 109, whereas the lower screws 108(b) maydiverge at an angle between 10° and 30° with respect to the centerline109. Although not shown, the anterior screw may angle posteriorly andthe posterior screw may angle anteriorly, as discussed above with regardto FIG. 14C.

As shown in FIG. 16D, to provide the height reduction of the plate 106Cdescribed in FIG. 8, the bottom surfaces 136A-136D of the spacer bodies102A-102D may be modified to define guide grooves 1600 that align withthe boreholes 110 _(C2) and 110 _(C4) of the plate 106C. As such, whenthe screw 108 is inserted into the boreholes 110 _(C2) or 110 _(C4), thescrew will pass through an interior of the boreholes 110 _(C2) or 110_(C4) and through the guide groove 1600 before penetrating into thecortical bone of the vertebral body (e.g., vertebral bodies 202 and204).

The spinal implant 100 including the plate 106C enables a surgeon or anyother medical professional working in the spinal region may avoidinterference with the iliac crest when working near the sacrum using theassembled spinal implant having the plate 106C. The plate 106C alsoallows for the removal of less bone in the event that osteophyte ispresent.

FIGS. 17A-17C illustrate another example spinal implant as generallypositioned in the intervertebral disc space between two vertebral bodies202 and 204. The spinal implant 100 may include any of the spacer bodies102A-102D, as modified in FIG. 16D, and the plate 106D, thus providingan asymmetric divergence of the screws 108. As shown in FIG. 17B, theupper screws 108 and the lower screws 108 diverge at an asymmetric anglefrom a midline 109 of the implant 100. As shown, the upper screws 108(a)may diverge at an angle between 0° and 10° with respect to thecenterline 109, whereas the lower screws 108(b) may diverge at an anglebetween 10° and 30° with respect to the centerline 109. Although notshown, the anterior screw may angle posteriorly and the posterior screwmay angle anteriorly, as discussed above with regard to FIG. 14C.

In the example of FIGS. 17A-17C, the spinal implant 100, and inparticular, the plate 106D is optionally configured to be mounted flushto certain portions of the anatomy in the medial-lateral plane, as wellas the cranial-caudal plane. As shown, the plate 106D provides for aportion 902 in which material associated with the plate 106D is removed.

Referring to FIGS. 18A-18B, there is illustrated a comparison of accesswindows that may be opened during a spinal implant procedure. FIG. 18Aillustrates the access window when one of plates 106C or 106D areutilized. The spinal implant 100 allows for an equivalent access windowwhen the placement of screws 108 is carried out through 0°. As shown,the plate 106C or 106D has an approximately 1 mm-2 mm overhang withrespect to the outer wall of the vertebral body 202. However, there isno overhang with respect to the vertebral body 204. In FIG. 18B, incontrast, illustrates the spinal implant using the plate 106A. Theaccess window in FIG. 18B, is slightly larger to accommodate insertionof the screws 108 through the boreholes in the slightly larger plate106A.

FIGS. 19A-19C illustrate another spinal implant 100B of the presentdisclosure. The spinal implant 100B is depicted in which the boreholes110 and screws 108 are aligned along the midline 125 of a plate 106E inaccordance with a fifth embodiment. The centralized location of theboreholes 110 and screws 108 presents less risk of the screws 108breaking through the anterior cortex, thus reducing the likelihood ofcausing vessel damage. In FIG. 19A, there is shown a side view of theplate 106E showing a side 160E. The lower borehole 110 _(E2) may beformed at an approximately 20° angle with respect to a lateral centerplane 161E of the plate 106E. The upper borehole 110 _(E1) may be formedat an approximately 20° angle with respect to the lateral center plane161E.

In the front view of FIG. 19C, the upper borehole 110 _(E1) may belocated a distance D_(U) from the lateral center plane 161E. The lowerborehole 110 _(E2) may be located a distance D_(L) from a lateral centerplane 161E. The distance D_(U) may range from approximate 2.75 mm to6.75 mm. Similarly, the distance D_(L) may range from approximately 2.75mm to 6.75 mm. Because of the symmetric shape of the plate 106E, theratio of D_(L):D_(U) is maintained at 1, thus D_(L) and D_(U) are equalfor all sizes of D_(L) and D_(U) implemented in the plate 106E. Theplate 106E may have a height H that ranges from approximately 15 mm to23 mm. The distance Q between the outer edges of the boreholes in avertical direction may range from approximately 12 mm to 20 mm, thusproviding approximately 1.5 mm of material between the outer edge of theborehole and the edge of the plate 106E. The distance U between theinner edges of the boreholes may range from approximately 0.5 mm to 8.5mm.

As shown in FIG. 19B, the above offsets of the central axis causes thescrews 108 inserted therein to diverge at symmetric angles about thelateral center plane 161E of the plate 106E. It is noted that centralaxis 153E and 155E of the lower and upper boreholes may be offset at anyangle between 5° and 20° with respect to the horizontal axis 154E and156E. Although not shown, the plate 106E may provide for asymmetricdivergence of the screws, as described with regard to the plate 106A.Other aspects of the plate 106E maybe similar to the plate 106A, forexample, the rear surface of the plate 106E may be curved to provide abetter fit with the outer walls of the vertebral bodies 202 and 204.

Referring now to FIG. 20, there is illustrated another spinal implant100C having a plate 106F in accordance with a sixth embodiment toprovide for alternative screw positions. The spinal implant 100C allowsthe surgeon or medical professional to minimize the opening required forplacement of the screws 108, as the plate 106F comprises boreholes 110that are proximate to a centerline 107F of the plate 106F.

In particular, the plate 106F may be configured similarly as the plate106B with boreholes 110 _(B2) and 110 _(B3) removed from the plate 106B.The lower borehole 110 _(B2) may be formed at an approximately 20° anglewith respect to a lateral center plane 161F of the plate 106F. The upperborehole 110 _(F1) may be formed at an approximately 20° angle withrespect to the lateral center plane 161F. This causes the screws 108inserted therein to diverge at symmetric angles about the lateral centerplane 161F of the plate 106F. It is noted that central axis 153F and155F of the lower and upper boreholes may be offset at any angle between5° and 20° with respect to the horizontal axis 154F and 156F. Althoughnot shown, the plate 106F may provide for asymmetric divergence of thescrews, as described with regard to the plate 106A.

The upper borehole 110 _(F1) may be located a distance D_(U) from thelateral center plane 161F. the lower boreholes 110 _(F2) may be locateda distance D_(L) from a lateral center plane 161F. The distance D_(U)may range from approximate 2.75 mm to 6.75 mm. Similarly, the distanceD_(L) may range from approximately 2.75 mm to 6.75 mm. Because of thesymmetric shape of the plate 106B, the ratio of D_(L):D_(U) ismaintained at 1, thus D_(L) and D_(U) are equal for all sizes of D_(L)and D_(U) implemented in the plate 106F. The plate 106F may have aheight H that ranges from approximately 15 mm to 23 mm. The distance Qbetween the outer edges of the boreholes in a vertical direction mayrange from approximately 12 mm to 20 mm, thus providing approximately1.5 mm of material between the outer edge of the borehole and the edgeof the plate 106B. The distance U between the inner edges of theboreholes may range from approximately 0.5 mm to 8.5 mm. Optionally, theboreholes 110 _(F2) and 110 _(F2) of plate 106F may be configured toenable the anterior screw to angle posteriorly, while and the posteriorscrew's trajectory may be straight or angled anteriorly.

FIGS. 21A-21D illustrate another spinal implant 100D having a plate 106Gin accordance with a seventh embodiment the present disclosure. Theplate 106G is configured to enable the use of three screws 108 with thespinal implant 100G when inserted into an intervertebral space betweentwo vertebral bodies. The plate 106G may be configured with two upperboreholes 110 _(G1) and 110 _(G3) and a lower borehole 110 _(G2). Asshow in FIGS. 21A and 21C, the upper boreholes may have similarcharacteristics as boreholes 110 _(B1) and 110 _(B3). In particular, theupper boreholes 110 _(G1) and 110 _(G3) may be formed having anapproximately 5° angle with respect to the lateral center plane 161G.The lower borehole 110 _(G2) may be formed having an approximately 20°angle with respect the lateral center plane 161G of the plate 106G. Asshow in FIG. 21B, the upper boreholes 110 _(G1) and 110 _(G3) may beformed having an approximately 20° angle with respect to the lateralcenter plane 161G. The lower borehole 110 _(G2) may be formed having anapproximately 20° angle with respect the lateral center plane 161G ofthe plate 106G.

As shown in FIGS. 21A and 21C, the above offsets of the centrallongitudinal plant causes the screws 108 inserted therein to diverge atasymmetric angles about the lateral center plane 161G of the plate 106G,whereas in FIG. 21B the screws 108 inserted therein to diverge atsymmetric angles about the lateral center plane 161G of the plate 106G.It is noted that the lower and upper boreholes may be offset at anyangle between 5° and 20° with respect to the lateral center plane 161G.

As shown in FIG. 21D, in accordance with the discussion of FIG. 14C, theupper borehole 110 _(G1) may be formed such that it is laterally offsetat approximately a 3° angle. The upper boreholes 110 _(G3) may be formedhaving a laterally offset at approximately a 1° angle. The divergence ofthe screws inserted into the boreholes 110 _(G1) and 110 _(G3) is shownin FIG. 21D.

FIGS. 22A-22C illustrate views of another embodiment of a spinal implant100 of the present disclosure. The spinal implant 200 may be anteriorlyinserted into an intervertebral space between two vertebral bodies 222and 220. For example, the spinal implant 200 may be used for L5-S1 andimpart stability to a lytic spondylolisthesis. The spinal implant 200includes an intervertebral spacer body 202. The intervertebral spacerbody 102 includes a pair of opposite sides 204. Each opposite side 204optionally has pyramid-shaped teeth 218 that are provided tofrictionally engage top and bottom surfaces of a vertebral body. Thespinal implant 200 also includes a plate 206. The plate 206 has a widthof 20 mm to 40 mm and a height of 10 mm to 50 mm. The plate 206 iscomprised of a front surface and a rear surface, and may be contoured tooptimally engage the vertebral bodies 222 and 220. The plate 206 mayinclude at least two upper boreholes 210 and at least two lowerboreholes 210, respectively, asymmetrically positioned about acenterline 207.

As shown in FIG. 22B, the upper screws 108(a) and the lower screws108(b) may diverge at an asymmetric angle from a midline 209 of theimplant 200. The screws 108 attach the plate 206 to the vertebral bodies(e.g., L5 and S1), between which the intervertebral spacer body 202 maybe inserted. The plate 206 is shaped such that the insertion angles ofthe screws 108 are such that a surgeon may use a straight screwdriver tothe insert the screws 108 into the boreholes 210 of the plate 206. Theplate 206 provides for ease of insertion and biomechanical integrity.The plate 206 defines a region to mate with the intervertebral spacerbody 202. A portion of the rear surface of the plate 206 is adapted tocontact a wall of the vertebral body (e.g., body 222).

With reference to FIG. 2C, the spacer body 202 includes a flange 221 anddefines a recess 223 that is adapted to engage a coupling 224 of theplate 206. The engagement of the flange 221 and the coupling 224prevents lateral and rotational movement of the plate 206 with respectto the intervertebral spacer body 202. A screw (not shown) may beinserted into a central hole of the plate 206 to secure the plate 206 tothe spacer body 202. The lower screws 108(b) may from an angle δ withrespect to longitudinal axis of the implant 200. The angle δ may beapproximately 20°. The divergent angles of the lower screws 108(b)increases the stability of the implant 200. In general, the top set ofscrews may be parallel and bottom set may be at an angle such that inmultiple levels, the bottom (diverging) set of screws do not interferewith the top (parallel) set of screws. The angle δ may be fixed by theaforementioned engagement of the locking threads within the boreholeswith the complementary locking threads of the screw heads. The spacerbody 202 may have a length to width ratio of approximately between 0.3and 0.5 when used for, e.g., anterior procedures.

Many modifications and other embodiments of the disclosure set forthherein will come to mind to one skilled in the art to which thisdisclosure pertains having the benefit of the teachings presented in theforegoing description. Therefore, it is to be understood that thedisclosure is not to be limited to the specific embodiments disclosedand that modifications and other embodiments are intended to be includedwithin the scope of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

What is claimed:
 1. A spinal implant for insertion into an invertebraldisc space between a superior and inferior vertebral bodies, the spinalimplant, comprising: a spacer body comprising a proximal base portion, adistal end, a first side wall and an opposing second side wall; and aplate having a first side, a second side, a front surface, a rearsurface and a pair of opposing coupling flanges that extend from therear surface, the front facing surface defining a first radius ofcurvature proximate the first side of the plate and a second radius ofcurvature proximate the second side of the plate, the rear surfacedefining a curved face extending away from a top edge of the plate in adirection towards the distal end of the spacer body to a flat formed onthe rear surface proximate the opposing coupling flanges, the curvedface defining a first curvature extending between a central verticalaxis of the plate and the first side and defining a second curvatureextending between the central vertical axis and the second side suchthat the entire first curvature is asymmetric with the second curvature,the plate forming an upper borehole and a lower borehole that arerespectively positioned about a lateral center plane of the plate,wherein the plate is secured to the spacer body by a mechanical couplingof the opposing coupling flanges, wherein the upper borehole and thelower borehole are adapted to each receive a bone screw to secure thespinal implant within the invertebral disc space, wherein the firstradius of curvature and second radius of curvature are different.
 2. Thespinal implant of claim 1, wherein at least one of the pair of opposingcoupling flanges has an inward pointing projection that is adapted to bereceived within a respective recess included in a corresponding one ofthe first side wall and the second side wall.
 3. The spinal implant ofclaim 2, wherein the recess extends along only a portion of therespective first side wall and the second side wall.
 4. The spinalimplant of claim 2, wherein the recess extends along an entirety of therespective first side wall and the second side wall.
 5. The spinalimplant of claim 1, wherein the proximal base portion has a width lessthan a width of the spacer body as measured between the first side walland the second side wall.
 6. The spinal implant of claim 1, wherein anoverall width of the proximal base portion and the coupling flanges,when combined, is approximately equal to the width of the spacer body.7. The spinal implant of claim 1, wherein the upper borehole and thelower borehole include locking threads that are adapted to receive athreaded head of the bone screw to lock the bone screw at a fixed anglewith respect to the plate.
 8. The spinal implant of claim 1, wherein thefirst side of the plate is sized and configured for location at ananterior position with respect to the invertebral disc space and thesecond side of the plate is located at a posterior position with respectto the invertebral disc space.
 9. The spinal implant of claim 8, whereinthe upper borehole is located proximate the first side of the plate andthe lower borehole is located proximate the second side of the plate.10. The spinal implant of claim 9, wherein the upper borehole isconfigured such that a first bone screw inserted into the upper boreholeis angled in a direction towards the second side wall of the spacerbody, wherein the lower bore hole is configured such that a second bonescrew inserted into the lower borehole is angled in at least one of astraight direction or a direction towards the first side wall of thespacer body.
 11. The spinal implant of claim 1, wherein the upper borehole includes a first upper borehole formed proximate to the first side,and a second upper borehole formed proximate to the second side, whereinthe first upper borehole and the second upper borehole are respectivelypositioned about the lateral center plane of the plate.
 12. The spinalimplant of claim 1, wherein the lower borehole includes a first lowerborehole formed proximate to the first side, and a second lower boreholeformed proximate to the second side, wherein the first lower boreholeand the second lower borehole are respectively positioned about thelateral center plane of the plate.
 13. The spinal implant of claim 1,wherein the lower borehole has a central axis that is formed at anapproximately 5° to 20° angle with respect to the lateral center planeof the plate, and wherein the upper borehole has a central axis that isformed at an approximately 5° to 20° angle with respect to the lateralcenter plane of the plate.
 14. The spinal implant of claim 13, wherein afirst bone screw inserted into the upper borehole and a second bonescrew inserted into the lower borehole diverge at symmetric angles aboutthe lateral center plane.
 15. The spinal implant of claim 13, wherein afirst bone screw inserted into the upper borehole and a second bonescrew inserted into the lower borehole diverge at asymmetric anglesabout the lateral center plane.
 16. The spinal implant of claim 1,wherein the lower borehole is located a distance D_(L) from the lateralcentral plane of the plate, and wherein the upper borehole is located adistance D_(U) from the lateral central plane of the plate, and whereina ratio of D_(L):D_(U) is 1 to
 1. 17. The spinal implant of claim 1,wherein the lower borehole is located a distance D_(L) from the lateralcentral plane of the plate, and wherein the upper borehole is located adistance D_(U) from the lateral central plane of the plate, wherein thedistance D_(U) ranges from approximately 2.75 mm to 6.75 mm and thedistance D_(L) ranges from approximately 2.75 mm to 6.75 mm.
 18. Thespinal implant of claim 1, wherein the plate has a height H that rangesfrom approximately 15 mm to 23 mm and the distance Q between the outeredges of the upper borehole and the lower borehole in a verticaldirection may range from approximately 12 mm to 20 mm.
 19. The spinalimplant of claim 1, the spacer body includes a top surface and bottomsurface side each having outwardly extending pyramid-shaped teeth. 20.The spinal implant of claim 1, wherein the spacer body defines a centralwindow extending there through, and wherein the first side wall and thesecond side wall define at least one window.
 21. The spinal implant ofclaim 1, wherein the first radius of curvature greater extends furthertowards a center line of the front surface of the plate than the secondradius of curvature.
 22. The spinal implant of claim 1, wherein thefirst radius of curvature is greater than the second radius ofcurvature, wherein the front surface is sized and configured tocorrespond to an outer wall of at least one of the superior and inferiorvertebral bodies.
 23. The spinal implant of claim 1, wherein the spacerbody has a length L and a width W such that the length to width rangesfrom approximately 1.8 to 3.2.
 24. The spinal implant of claim 23,wherein the length L ranges from approximately 35 mm to 55 mm and thewidth W of approximately 18 mm.
 25. The spinal implant of claim 1,wherein the spacer body has a length L and a width W such that thelength to width ranges from approximately 1.59 to 2.5.
 26. The spinalimplant of claim 25, wherein the length L ranges from approximately 35mm to 55 mm and the width W of approximately 22 mm.